In particular,bottlenose dolphinsand sea turtles are dying in record numbers, and the evidence is stronger than ever that their demise is connected to the spill, according toDoug Inkley, senior scientist for the National Wildlife Federation, which issued the report. (See "Gulf Oil Spill: One Year Later.")

The Deepwater Horizon oil rig exploded on April 20, 2010, killing 11 people and spewing more than 200 million gallons (750 million liters) of oil into the Gulf of Mexico. Since then, various government agencies and nonprofits, including the National Wildlife Federation, have been studying the region's wildlife to track the impacts of the oil.